数组按索引变量排序

Question

I'm having some difficulties sorting a simple array that looks like this:

Array
(
    [3] => Array
        (
            [0] => EU West (Ireland)
            [1] => eu-west-1
        )

    [7] => Array
        (
            [0] => South America (Sao paulo)
            [1] => sa-east-1
        )

    [0] => Array
        (
            [0] => US East (Virginia)
            [1] => us-east-1
        )

    [4] => Array
        (
            [0] => Asia Pasific (Tokyo)
            [1] => ap-northeast-1
        )

    [2] => Array
        (
            [0] => US West (Oregon)
            [1] => us-west-2
        )

    [1] => Array
        (
            [0] => US West (N. California)
            [1] => us-west-1
        )

    [5] => Array
        (
            [0] => Asia Pasific (Singapore)
            [1] => ap-southeast-1
        )

    [6] => Array
        (
            [0] => Asia Pasific (Sydney)
            [1] => ap-southeast-2
        )

)

I want to sort this array on Index. I used ksort() but it doesn't work, it leaves an output 1.

Answer 1

ksort() doesn't return the sorted array, but rather it sorts the array in place. After calling ksort($array), the contents of $array will be sorted. The function returns whether the sort was successful or not.

Example:

$array = array(1 => 1, 20 => 1, 5 => 1);

echo "Before ksort():
";
print_r($array);

if (ksort($array)) {
    echo "ksort() completed successfully.
";
}

echo "After ksort():
";
print_r($array);

The above prints:

Before ksort():
Array
(
    [1] => 1
    [20] => 1
    [5] => 1
)
ksort() completed successfully.
After ksort():
Array
(
    [1] => 1
    [5] => 1
    [20] => 1
)

You shouldn't check the return value of ksort() though, since ksort() can only fail in situations in which it doesn't even get to return a failure. Therefore, the function will either return true or the script will die, in which case the return value is irrelevant (it will always be true).